Manufacture and production of hard metal alloys



Patented Nov. 12, 1935 PATENT OFFICE MANUFACTURE AND PRODUCTION OF HARD METAL ALLOYS Alan Richard Powell and Ernest Robert Box, London, England, assignors to Johnson Matthey & Company Limited, London, England, a British company I No Drawing. Application October 5, 1933, Serial No. 692,357. In Great Britain October 11, 1932 3 Claims.

This invention relates to the manufacture and production of hard metal alloys especially useful for tipping the points of gold nibs and the points of compass needles. 5 is tipped with alloys having a high content of platinum group metal as such alloys, besides being extremely hard, are absolutely unaffected by any corroding agent; there exists however, a large demand for a less costly hard alloy for use in tipping the nibs used in the cheaper grades of fountain pens and it is the object of this invention to provide such an alloy.

Hard alloys consisting of a carbide, .boride or silicide of metals of the tantalum and tungsten groups cemented with manganese or with a metal or alloy of the iron group and prepared by sintering in hydrogen bars formed by compressing intimate mixtures of the constituents have been used for tipping the ends of high speed cutting tools but such alloys cannot be broken into suificiently small pieces for use in tipping pen nibs. If these alloys be melted down in an electric furnace the resulting product is extremely hard and very difilcult to break down to small pieces and even slit when soldered on to a gold nib.

We have now found that satisfactory hard alloys for use in tipping gold nibs comprise a mixture of at least four elements at least one being selected from each of the following groups, (a) tungsten, molybdenum, (50 to 75 per cent by weight), (b) iron, cobalt, nickel (5 to 25 per cent by weight) (0) platinum, ruthenium, osmium (2 to 40 per cent by weight) (01) carbon, silicon boron, (0.5 to 5 per cent by weight) The sum of the atomic percentages of the group ((1) elements used should be equal to or less than the sum of the atomic percentages of the group (a) elements used, and the amount of the group (b) elements used should be at least 15 atomic per cent of the amount of the group (a) elements The elements of group (11) besides hardening the alloy have a powerful deoxidizing and degassing action on the molten alloys so that the The best class of nib when such pieces are obtained they cannot be.

resulting castings are dense and quite free from porosity. In addition boron imparts to the alloys a highly desirable white colour. A

The best alloys are those the proportions of the components of which are within the following ranges:- 5

Per cent by weight Platinum, ruthenium, osmium From 2 to 40 Tungsten From 50 to '70 Cobalt and/or nickel From 5to 25 10 Boron and/ or carbon and/ or silicon From 0.5 to 5 Part of the tungsten, not exceeding 10 per cent by weight, may be replaced by molybdenum but an excess of the latter metal is inadvisable because 15 it forms a readily volatile oxide at the temperatures at which the points are welded onto the gold nibs or the like.

In making the alloys the constituents may be mixed together in the form of powders or small 20 grains and the mixture melted in a suitable furnace, as for example an electric furnace of the induction, resistance or arc type. We prefer however, to add the element of group (d) in the form of an alloy with the element of group (a) 25 or (b), for example carbon may be added as tungsten carbide, boron as cobalt boride, and silicon as cobalt or tungsten silicide.

The following examples give the percentage compositions of hard alloys which have proved 30 I very satisfactory, but the invention is not restricted to these examples.

the boron being added in the form of cobalt 40 boride.

Example 2 Per cent by weight Platinum 10 5 Ruthenium 15 Tungsten Cobalt 9 and Boron 1 the boron being added in the form of cobalt 50 .boride.

What we claim is: 1. A hard alloy obtained by melting a mixture offrom 50 to of tungsten, 0.5 to 5% of boron, 5 to 25% of an element from the group consisting of cobalt and nickel, and 2 to 4.0% of an element from the group consisting of platinum, ruthenium and osmium, the proportion of boron to tungsten being not greater than 11 to 184 and the proportion of the element from the group consisting of cobalt and nickel toctungsten being at least 9 to 184.

2. A hard alloy consisting of 20 per cent by weight of ruthenium, 67 per cent of tungsten, 12 per cent of cobalt and 1 per cent of boron.

3. A hard alloy conssting of 10 per cent by weight of platinum, 15 per cent of ruthenium, 65

per cent of tungsten, 9 per cent of cobalt and 1 5 per cent of boron.

ALAN RICHARD POWELL. ERNEST ROBERT Box. 

